Our customers want to verify the fail safety circuit in case of MCU failure.
If the voltage level of a port is measured, it is judged whether there is a failure.
In other words, to determine that the MCU has been damaged or that no SW has been written.
In case of erase the flash or use a MCU that has not been written anything, what we are wondering is what is the initial state of the port(GPIO).
Looking at Table 1-6 of the RM, there is reset state of each port. In case of PJ0, "Up" state.
I want to know the exact meaning of this "Up" state.
Question1. When the reset starts, how much voltage should be measured?
What is the size of the internal pullup resistor?
Question2. Out of reset, is this measured voltage level maintained? (Remember that there is no SW in the MCU).
According to our customer's measurements, when the reset starts, it is measured at 1.2 V for about 1.3 seconds, and then drops to 0V.